Search Results (17)

With the growing application of digital technologies in construction, reinforcement detailing and cutting are becoming increasingly refined. However, existing cutting methods struggle to meet the dual requirements of low waste and high computational efficiency when facing diverse rebar types, multiple splice points, and complex constraints. This paper proposes a hybrid optimization algorithm for large-scale rebar cutting that achieves efficient joint optimization of splice positions and cutting schemes. Numerical simulations verify the performance of the proposed algorithm under normal and uniform length distributions, with comparisons against traditional methods. Results show that the proposed method maintains the waste ratio below 1% for large-scale numerical datasets while achieving much higher computational efficiency than heuristic algorithms with good stability and scalability. Two engineering examples further validate this approach. In column longitudinal reinforcement, the waste ratio in each story was kept below 1%, and in precast bridge segmental beams, the method flexibly incorporated customized raw rebar lengths, reducing the waste ratio to as low as 0.4%. The proposed method effectively balances material utilization and cutting efficiency, offering a practical solution for intelligent rebar cutting across a wide range of components and construction scenarios. Full article

Steel reinforcement is one of the most important materials used in the construction industry. This research optimizes reinforcement bar fabrication by integrating Building Information Modeling (BIM) with visual programming in Dynamo. On-site rebar cutting and bending generate significant material waste, increasing costs and environmental impact. To address this, an intelligent Dynamo script was developed to extract detailed 3D rebar and 4D scheduling data from BIM models. The script optimizes material usage by specifying cut-off lengths to improve reuse and minimize waste. Validation through two real-world case studies demonstrated the method’s significant potential. Effectiveness was assessed using benchmarks comparing the number of bars saved, waste reduced, and overall cost savings. The study confirms that optimized fabrication significantly cuts waste and cost. Its effectiveness, however, varies with rebar type and structural component, with the most significant gains observed in medium-length bars and pile caps. By offering a novel tool for sustainable construction, this research advances BIM-enabled reinforcement design and material optimization. Full article

As cities densify, deep underground infrastructure construction such as mass rapid transit (MRT) systems increasingly demand smarter, digitalized, and more sustainable approaches. RC diaphragm walls, essential to these systems, present challenges due to complex rebar configurations, spatial constraints, and high material usage and waste, factors that contribute significantly to carbon emissions. This study presents an AI-assisted rebar optimization framework to improve constructability and reduce waste in MRT-related diaphragm wall construction. The framework integrates the BIM concept with a custom greedy hybrid Python-based metaheuristic algorithm based on the WOA, enabling optimization through special-length rebar allocation and strategic coupler placement. Unlike conventional approaches reliant on stock-length rebars and lap splicing, this approach incorporates constructability constraints and reinforcement continuity into the optimization process. Applied to a high-density MRT project in Singapore, it demonstrated reductions of 19.76% in rebar usage, 84.57% in cutting waste, 17.4% in carbon emissions, and 14.57% in construction cost. By aligning digital intelligence with practical construction requirements, the proposed framework supports smart city goals through resource-efficient practices, construction innovation, and urban infrastructure decarbonization. Full article

The integration of Building Information Modeling (BIM) and Digital Twin (DT) technologies offers new opportunities for enhancing reinforcement design and on-site constructability. This study addresses a current gap in DT applications by introducing an intelligent framework that simultaneously automates rebar layout generation and reduces rebar cutting waste (RCW), two challenges often overlooked during the construction execution phase. The system employs heuristic algorithms to generate constructability-aware rebar configurations and leverages Industry Foundation Classes (IFC) schema-based data models for interoperability. The framework is implemented using Autodesk Revit and Dynamo for rebar modeling and layout generation, Microsoft Project for schedule integration, and Autodesk Navisworks for clash detection. Real-time scheduling synchronization is achieved through IFC schema-based BIM models linked to construction timelines, while embedded clash detection and constructability feedback loops allow for iterative refinement and improved installation feasibility. A case study on a high-rise commercial building demonstrates substantial material savings, improved constructability, and reduced layout time, validating the practical advantages of BIM–DT integration for RC construction. Full article

As the construction industry shifts from an extensive development model to one characterized by intelligent structural systems, the imperative to enhance productivity and management efficiency has emerged as a critical challenge. Conventional rebar construction processes heavily rely on manual operations—such as on-site rebar cutting, manual transcription of material lists, and decentralized processing—which are susceptible to subjective errors and often result in significant material waste. This issue is particularly pronounced in large-scale projects, where disorganized management of rebar quantities and placements exacerbates inefficiencies. To address these challenges, this study proposes an integrated approach that synergistically combines a genetic algorithm-based rebar-cutting optimization model with BIM technology, thereby optimizing rebar management throughout the construction process. The research is structured into two primary components. Firstly, a one-dimensional mathematical model for rebar-cutting optimization is developed, incorporating an innovative real-number encoding strategy within the genetic algorithm framework to maximize material utilization. A case study conducted on a pump station project reveals that the utilization rates for 32 mm and 16 mm rebar reach 86.76% and 93.90%, respectively, significantly exceeding the industry standard of 80%. Secondly, an automated batch modeling tool is developed using C# and the Revit API, which enables the efficient generation of rebar components; a unique coding system is employed to establish a bidirectional mapping between the digital model and the physical rebar, ensuring precise positioning and effective information management. Overall, this integrated method—encompassing rebar-cutting optimization, digital modeling, and on-site intelligent management—not only mitigates material waste and reduces production costs but also markedly enhances construction efficiency and accuracy in complex projects, thereby providing robust technical support for the seamless integration of intelligent construction and industrialized building practices. Full article

Rebar procurement inefficiencies, such as inaccurate quantity estimation and misaligned delivery schedules, often lead to excessive waste, supply shortages, and project delays. While existing optimization methods reduce cutting waste, their effectiveness diminishes without integration into supply chain management (SCM). This study presents an integrated framework to optimize rebar processing and supply chain management (SCM) by leveraging Building Information Modeling (BIM) and data-driven optimization strategies. A 24-floor case study validated the approach, optimizing continuous main rebars into special lengths and combining discontinuous lengths into cutting patterns based on special lengths. Rebar orders were organized into 12 batches, each meeting a 15-ton minimum and requiring order placement at least two months in advance. An activity database integrated rebar optimization with the construction schedule, facilitating SCM analysis. BIM automation streamlined procurement by generating Bar Bending Schedules (BBSs) and synchronizing rebar tracking with real-time updates, improving coordination, efficiency, and project outcomes, particularly in high-rise building projects. Full article

The growing demand for reinforced concrete (RC) structures, driven by population growth, significantly contributes to carbon emissions, particularly during the construction phase. Steel rebar production, a major contributor to these emissions, faces challenges due to high material consumption and waste, often stemming from market-length rebar and conventional lap splices, impeding decarbonization efforts. This study introduces a comprehensive strategy to minimize rebar consumption and waste, advancing decarbonization in the civil and construction industry. The strategy integrates a special-length-priority minimization algorithm with lap splice position adjustments or couplers to reduce rebar consumption, waste, and carbon emissions. A case study evaluates distinct scenarios regarding rebar consumption. The study demonstrates that conventional rebar practices, such as market-length rebar and lap splices, lead to excessive consumption and waste, impeding decarbonization. Couplers significantly reduce rebar requirements, though cutting waste remains when combined with market-length rebar. Special-length-priority optimization with lap splice adjustments demonstrates greater efficiency in reducing consumption while minimizing cutting waste, proving effectiveness. The combination of special-length-priority optimization and couplers achieves the greatest reductions in rebar consumption, waste, and carbon emissions, making it the most efficient strategy for future construction projects. These findings emphasize the importance of optimizing rebar consumption in advancing decarbonization and promoting sustainable practices in the civil and construction industry. Full article

Global economic fluctuations as exemplified by the recent COVID-19 financial crisis significantly impact the construction industry, particularly steel rebar supply chain and procurement. This impedes engineers’ efforts toward achieving near-zero rebar-cutting waste due to dynamic rebar minimum order quantities and maximum lengths imposed by steel mills. This study addresses the challenge of achieving near-zero rebar-cutting waste by proposing a model that simulates the level of optimization in minimizing rebar-cutting waste amidst such dynamics. The model was implemented in a case study involving reinforced concrete columns in a high-rise building. While achieving near-zero waste consistently proved challenging, particularly for greater than 50 tons of minimum quantity, the study identified a maximum 12 m rebar variant that attained this target regardless of minimum order quantity. Nonetheless, this study introduces a real-time decision-support system for rebar procurement, empowering engineers to optimize usage and minimize waste. This system facilitates near-zero rebar-cutting waste levels in response to rebar procurement requirement dynamics. Full article

The construction industry generates significant CO₂ emissions and reinforcing bars (rebar), which are a major contributor to this environmental impact. Extensive research has been conducted to address this particular issue. Recent research advances have introduced algorithms to reduce rebar waste and consumption, demonstrating the feasibility of achieving near-zero rebar cutting waste (N0RCW) through the consideration of special-length rebars. However, conventional lap splices, the most common rebar joint method, continue to consistently consume excessive quantities of rebar, despite extending beyond their mandated zones. Conversely, couplers can eliminate rebar lengths required for lapping splices, reducing the usage of rebar. Applying special-length rebars and couplers in heavily loaded structures like diaphragm walls can also significantly reduce rebar usage and cutting waste, consequently reducing CO₂ emissions and the environmental and economic impacts. This research aims to optimize rebar consumption and sustainability in diaphragm wall structures by integrating mechanical couplers with a special-length rebar approach. A case study confirmed a substantial reduction in purchased rebar usage (17.95% and 5.38%), carbon emissions (15.24% and 2.25%), water footprint (17.95% and 5.38%), and environmental impact (95.18% and 30.27%) compared to the original design and recent diaphragm wall study, respectively. The broad implementation of the proposed method across various buildings and infrastructure projects could further multiply these benefits, enabling the achievement of the sustainable development goals (SDGs) adopted by the United Nations to foster sustainable construction. Full article

The production of steel rebar is an energy-intensive process that generates CO₂ emissions. In construction, waste is generated by cutting stock-length rebar to the required lengths. The reduction rate achieved in most previous studies was limited due to adherence to lap splice positions mandated by building codes and the use of stock-length rebar. A previous study demonstrated a significant reduction in rebar usage and cutting waste, approaching zero, upon optimizing the lap splice position, reducing the number of splices, and utilizing special-length rebar. However, the reference length used to determine the special-length rebar was not clearly optimized. This study proposes a special length priority optimization model to minimize wall rebar usage and waste by reducing the number of splices while simultaneously ensuring an optimal reference length. The proposed model was validated using a case study wall with a standard hook anchorage at the top of the wall reinforcement. The optimization model reduced rebar cutting waste to 0.18% and decreased rebar usage from the original design by 16.16%. Full article

The construction of reinforced concrete (RC) structures inevitably consumes an excessive number of rebars, leading to significant cutting waste and carbon emissions. Extensive research has been conducted to minimize this issue and its consequences; however, these methods consistently consume a substantial number of rebars. This includes a previous study that utilizes the lap splice position optimization and special-length rebar concept without considering the lapping zone regulation. Moreover, conventional lap splices pose inherent drawbacks that could jeopardize the structural integrity of RC members. In contrast, mechanical couplers eliminate the need for rebar lapping, effectively reducing rebar consumption. This research aims to evaluate the impact of an integrated mechanical coupler and special-length-priority minimization algorithm on the reduction in rebar consumption and cutting waste in RC columns, achieving near-zero cutting waste. To validate the effectiveness of the proposed algorithm, it was applied to the column rebars of an RC building. The results revealed a significant reduction in the ordered rebar consumption by 18.25%, accompanied by substantial reductions in the cutting waste (8.93%), carbon emissions (12.99%), and total costs (9.94%) compared with a previous study. The outcomes provide the industry with insights into further reducing rebar consumption and its related consequences. Applying the proposed algorithm to various construction projects will further amplify the corresponding benefits. Full article

Rebar usage and cutting waste contribute significantly to global greenhouse gas emissions, mainly CO₂ and CH₄. Researchers have explored various means to minimize cutting waste; however, these studies have yet to address reducing splices and utilizing a single specific special-length rebar. Hence, this study proposed an algorithm to minimize rebar usage and reduce rebar-cutting waste to less than 1% (near-zero rebar-cutting waste). The algorithm involves two main steps: (1) reducing the number of splices by utilizing special-length rebar and (2) adjusting the rebar accordingly based on the obtained special-length rebar. The algorithm was applied to the column rebars of an RC building to validate its effectiveness. The results confirmed a reduction in rebar usage by 3.226 tons (17.76%), a cutting waste rate of 0.83% (near-zero rebar-cutting waste achieved), a reduction of 11.18 tons in CO₂ emissions, and a cost reduction of USD 3741. Employing the proposed algorithm in RC building and structure projects will amplify the corresponding benefits and contribute to the achievement of SDGs adopted by the United Nations to ensure sustainable resource usage and the acceleration of sustainable and green construction practices. Full article

While various approaches have been developed to minimize rebar cutting waste, such as optimizing cutting patterns and the lap splice position, reducing rebar usage by minimizing the number of splices remains uninvestigated. In response to these issues, a two-stage optimization algorithm was developed that prioritizes the use of special-length rebar to achieve a near-zero rebar cutting waste (N0RCW) of less than 1%, while also reducing overall rebar usage. The two-stage algorithm first optimizes the lap splice position for continuous rebar considering the use of a special-length rebar, which reduces the number of splices required. It then integrates a special-length minimization algorithm to combine the additional rebar. The algorithm was applied to beam structures in a small-sized factory building project, and it resulted in a notable reduction of 29.624 tons of rebar, equivalent to 12.31% of the total purchased quantity. Greenhouse gas emissions were reduced by 102.68 tons, and associated costs decreased by USD 30,256. A rebar cutting waste of 0.93%, which is near zero, was achieved. These findings highlight the significant potential of the proposed algorithm for reducing rebar waste and facilitating sustainable construction practices. The algorithm is also applicable to other reinforced concrete projects, where the associated advantages will be amplified accordingly. Full article

It is important to apply the Length types of Processed Rebar Simplification (LPRS) to rebar work for improving work efficiency and reducing labor in construction fields. However, when used excessively, LPRS can also bring about adverse results, as the increase in the amount of wasted rebars can scale with the cutting process, leading to an increase in material cost. Therefore, it is crucial to find a proper level of simplification for considering labor and material cost together. In this study, various simplification tests were conducted based on BIM software to quantitatively validate the variation of the amount of rebar and LPRS according to the simplification. These tests were conducted for each member and the shape of the building, using the data of five projects, by dividing the unit of simplified rebar length into three cases. The research analysis showed that simplifying the unit of rebar lengths to 500 mm and 1000 mm increased the amounts of materials at a greater rate, making them undesirable. Further, it was recognized that irregular slabs, compared to regular slabs, more efficiently reduced the number of LPRS when adopting simplification methods. This study is expected to contribute to preventing material costs from increasing excessively by quantitatively analyzing the impact level of simplification on the amount of rebar materials and LPRS. Full article

Rebar engineering in the construction industry lacks effective technical means and has a high processing cost and high waste rate. Under the background of intelligent construction, the centralized processing mode of steel bars in prefabricated factories realizes the automatic processing of steel bars and improves the processing efficiency of steel bars. Using the C# programming language, combined with Revit secondary development technology, the automatic generation of the rebar model and the automatic export of rebar drawing are realized, which saves time for the designers to build the model. The calculation method of the cutting length of the steel bar is analyzed in this paper, which can be used as a reference for the subsequent optimization research of steel bar cutting. The assembly position information of the steel bar was introduced into an Excel table to help realize the automatic assembly of the steel bar cage and the intelligent construction of the steel bar. Combined with mixed reality technology, project personnel can interact with the reinforced BIM model through the mixed reality device Hololens2 to guide construction remotely. Full article